Assalamu alaikum wa rahmatulllahi wa barakatuh.
(Peace be upon you dear visitor.)
In my tests, I saw that Floodlight discovers an unknown host per switch as in the figure below.
I have Floodlight (FL), Mininet (MN) and Open VSwitch (OVS) installed in the same machine where Ubuntu 14.04 LTS x64 is running. As far as I know, OVS 2.0.1 supports kernel from 2.6.32 to 3.10. Since my Ubuntu kernel is 3.13, this may be the source of problem. Update of OVS or downgrade of Ubuntu kernel may solve the problem but I have another simple, not that good, solution.
With the help and advise of Hung-Wei Chiu from Floodlight-Developers group, I noticed that there are many IPv6 packets in the FL logs as he had told. This unknown IPv6 addresses were the same as MAC addresses of switches or hosts. As a solution to this problem, I disabled IPv6 in my computer.
In order to disable IPv6, you must append the three lines of code as in below to the file located in /etc/sysctl.conf . Note that you need root privileges.
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1
After modification, you can either reboot your computer or execute sudo sysctl -p command in terminal.
However, this method may not work as expected. (Well, it did not work for me) Alternatively, there is another way of disabling IPv6 in Linux. Using your favorite text editor, open /etc/default/grub file. Then, add ipv6.disable=1 to the GRUB_CMDLINE_LINUX line. In my computer (Ubuntu 14.04 LTS x64), it was like:
GRUB_CMDLINE_LINUX=""
After change:
GRUB_CMDLINE_LINUX="ipv6.disable=1"
After this modification, you must update grub with executing the command sudo update-grub . Finally, reboot your computer and problem solved!
Assalamu alaikum wa rahmatulllahi wa barakatuh.